A Challenge to “Pro-Choice” Catholic Politicians

How can the “pro-choice” crowd argue against the following quotation from the founding document of our country, the Declaration of Independence?
“We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.–That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed.”
If God is the Creator, and has given Life to a person, how can anyone take that Life without just cause. Surely, there is enough medical evidence, what with ultrasound and other techniques, that a fetus is alive in the womb, has a heartbeat, etc. So, who can take that Life except the Creator? In fact, as the Declaration says, Governments are instituted to “secure these rights.”
Finally, how can supposed Catholics in the Congress, that legislative body charged with “securing those rights” and passing laws to do so, claim to be pro-choice? How about the Constitution which members of Congress, the Judiciary and even the President take an oath to uphold? It says: “No state shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any state deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.” So, a person with unique DNA is not a person until it exits the womb or, it doesn’t deserve equal protection while in the womb? Preposterous!
[Answers from anyone who claims to be a Pro-Choice Catholic politician and defender of the Constitution?]